1. Field of the Invention
In general, the present invention relates to a process for removing a wide variety of materials from liquids. More particularly, this invention relates to a process for removing organic and/or inorganic materials from aqueous and/or non-aqueous liquids by contact with non-stoichiometric carbon-sulfur compounds under adsorption conditions.
2. Description of the Prior Art
One method for removing organic and/or inorganic materials from liquids is by using activated carbon as an adsorbent. This method has found particular application in removing organic contaminants from municipal and/or industrial waste waters as well as from the effluents from secondary biological treating processes (see, for example, U.S. Pat. Nos. 3,244,621, 3,455,820, 3,658,697 and 4,053,396, the disclosures of which are incorporated herein by reference).
However, conventional activated carbons have been observed to have several limitations. For example, they show little amenity to adsorb many common, low molecular weight, polar organics found typically in petrochemical effluents (see C. T. Lawson and J. A. Fisher, "Water--1973", AIChE Symposium Series 135, Vol. 70, pp. 544-584, 1974, the disclosure of which is incorporated herein by reference). In addition, inorganic species, particularly toxic materials such as metal ions and cyanides, are adsorbed poorly on conventional carbons (see T. Maruyama, S. A. Hannah and J. M. Cohen, Journal Water Pollution Control Federation, Vol. 47, No. 5, pp. 962-975, the disclosure of which is incorporated herein by reference). Further, desorption of certain aromatics (e.g., alkylbenzenes, nitro-aromatics, and the like) from conventional activated carbon is difficult due to the high binding energy of said aromatics on the carbon (see B. R. Puri, "Surface Complexes on Carbons", Chapter in Chemistry and Physics of Carbon, Vol. 6, Marcel Dekker, 1970; B. R. Puri, "Adsorption at Interfaces", ACS Symposium Series, Vol. 8, pp. 212-224, 1975; B. R. Puri et al, Carbon, Vol. 11, pp. 329-336, 1973, the disclosures of which are incorporated herein by reference). As such, regeneration of the spent activated carbon adsorbent becomes expensive in that high temperatures (e.g., 900.degree.-1000.degree. C.) and long contact times are required. The high temperatures result in destruction of the adsorbate as well as loss of carbon by attrition and burn-off. As such, carbon makeup costs become excessive.
Therefore, in view of the inadequacies of conventional activated carbon adsorbents, there is a need for an inexpensive adsorbent which can remove materials from aqueous and/or non-aqueous liquids effectively without the difficulties mentioned previously.